The apparent demise of the Asian date mussel Musculista senhousia in Western Australia: or using acts of god as an eradication tool

Abstract

Musculista senhousia (Benson in Cantor, 1842) is a small thin-shelled mytilid inhabiting intertidal and shallow subtidal sediments. Prior to 2000, M. senhousia was widespread in the Swan River estuary, Perth, Western Australia. In 2000 the Perth region experienced its largest recorded summer rainfall event, with over 270 GL entering the estuary. The rainfall formed a freshwater lens over much of the river and a subsequent toxic algal bloom of the cyanobacterium Microcystis aeruginosa. M. aeruginosa produces a toxin microcystin, known to have adverse effects upon molluscs. Surveys to assess the status of M. senhousia in the estuary in 2007 failed to find any individuals. We suggest the apparent death of M. senhousia from the estuary may be attributable to a combination of high seasonal variability in the mussel’s populations, high summer rainfall reducing salinity, and a toxic algal bloom that eliminated any remaining M. senhousia individuals.